Kawasaki fr691v smokes badly

Compression checks as good so I wasn’t really leaning towards a ring/bore issue. What are valve seals like in these? Bad seals could be metering oil down into the cylinder, which may also be what protected it from destruction from overheating.

If you like the mower and cant get the kawi running right (which I think you’ll be able to), dont overlook a harbor freight predator swap.
 
I bought a rebuild and rering kit from pats small engine. The connecting rod and crankshaft bearing surfaces all look brand new. I will compare the current piston rings and report back.
 
I come bearing info. I measured the rings. First off when you place each ring from the opposing piston on top of each other the looked and felt the same such as the two top rings on each other from each piston. Here are the ring gap measurements. The interesting thing is the bad cylinder has better ring gaps. I am also including the factory service manual specs. As you can see good or bad piston the rings are severely above specification. The pictures of the piston rings are in order of good cylinder top then middle ring then bad cylinder top then middle ring. You can also see how shiny both bores are by the reflection of the rings.
IMG_2157.webp
IMG_2159.webp

IMG_2150.webp
IMG_2154.webp
IMG_2155.webp
IMG_2156.webp
 
Those are the old rings? The gap is not the problem then, the rings have probably lost tension from being overheated. Do you know for sure which ring came from which cylinder? swap them and measure again.

BTW, don't hone those cylinders too much.
 
spasm3 said:
Those are the old rings? The gap is not the problem then, the rings have probably lost tension from being overheated. Do you know for sure which ring came from which cylinder? swap them and measure again.

BTW, don't hone those cylinders too much.
Click to expand...
Yes they are the old rings. Im not sure what the spring tension is supposed to feel like but they were very springy and i had to really spiral them into the cylinder. They did not just pop in.
 
joegreen said:
Yes they are the old rings. Im not sure what the spring tension is supposed to feel like but they were very springy and i had to really spiral them into the cylinder. They did not just pop in.
Click to expand...
The rings are shot. Their gap is over the service limit (per the image of the manual):
First ring .024"
Second ring .035"
Oil ring .43"
The ring gaps you measured (the black image above) are double the service limit, except the oil ring gap which is still close to the service limit.

There was water or coolant in the oil because it turned gray and mushy - lubrication was compromised.
There is a big mouse or other nest over one of the cylinders - cooling was compromised as well.

Measure also the piston to wall clearance to see if it's in specs. If it's in specs, just buy 2 sets of piston rings and call it a day. If it's not, then buy two pistons (corresponding to the current bore size) along with 2 sets of piston rings and call it a day.
 
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Dingle ball hone vs 3 stone hone? Im leaning towards the ball hone as the cylinders are round and don’t have any taper to try and correct.
 
joegreen said:
Dingle ball hone vs 3 stone hone? Im leaning towards the ball hone as the cylinders are round and don’t have any taper to try and correct.
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Whichever you have. You just want to cut any glaze and put a light crosshatch on while removing as little metal as practicable. Cutting oil is important. Ask the ringmaker for what crosshatch pattern and/or stone grade is preferred.
 
joegreen said:
Dingle ball hone vs 3 stone hone? Im leaning towards the ball hone as the cylinders are round and don’t have any taper to try and correct.
Click to expand...
Dingle ball is easy enough.

Make sure you wash that block thoroughly until a paper towel wiped on the dry cylinder is completely clean. I've used nylon brushes with dawn soap, don't miss a spot. Left over debris from the dingle ball or hone , will kill the new rings.
After washed , keep 3m pads away from the engine and parts .
 
spasm3 said:
Dingle ball is easy enough.

Make sure you wash that block thoroughly until a paper towel wiped on the dry cylinder is completely clean. I've used nylon brushes with dawn soap, don't miss a spot. Left over debris from the dingle ball or hone , will kill the new rings.
After washed , keep 3m pads away from the engine and parts .
Click to expand...
Do your final cleaning wipes with solvent and coffee filters, you might be surprised how well that works.
 
martinq said:
Do your final cleaning wipes with solvent and coffee filters, you might be surprised how well that works.
Click to expand...
^^^ This. Dingle ball it with a light lubricant like diesel. Use ATF and clean paper towels to wipe the cylinders clean. ATF is great for getting the grit out of there. When zero grit is present on the paper towels switch to a few wipes with Acetone.

Don't oil the cylinder wall before reassembly. Lightly oil the rings as you install them on the pistons, don't soak them. The initial friction between the ring and the cylinder wall is important to bed the rings.
 
Kawasaki coil failure is common problem. Amazon & eBay full of replacement coils. I have tried OEM and aftermarket they both fail after time.
 
Much better gaps on the new ones. Does not matter if you use a ball hone or flat stone just break the glaze so the new rings seat. Heck... Chainsaw folks break the glaze by hand with emery cloth and have sucess. Don't overthink it.

5w40, 15w40, or 20w50 will be all good choices. On zero turns these engines run hot oil temps.
 
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